# Error ## Error Attributes | Attribute | Type | Description | Examples | Stability | |---|---|---|---|---| | `error.type` | string | Describes a class of error the operation ended with. [1] | `timeout`; `java.net.UnknownHostException`; `server_certificate_invalid`; `500` |  | **[1]:** The `error.type` SHOULD be predictable and SHOULD have low cardinality. Instrumentations SHOULD document the list of errors they report. The cardinality of `error.type` within one instrumentation library SHOULD be low. Telemetry consumers that aggregate data from multiple instrumentation libraries and applications should be prepared for `error.type` to have high cardinality at query time when no additional filters are applied. If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`. If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes), it's RECOMMENDED to: * Use a domain-specific attribute * Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not. `error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used. | Value | Description | Stability | |---|---|---| | `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |  |